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  • 1
    ISSN: 1432-8798
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Sera obtained from 137 cervical cancer patients were analysed for the presence of antibodies to the human papillomavirus (HPV) type 16 proteins E6 and E7 by the aid of different assays, i.e. ELISA using as antigen either synthetic peptides or the complete E7 protein and radio-immunoprecipitation (RIPA) which uses the viral protein made by in vitro transcription/translation. In agreement with previous reports, reactivity to the E7 protein was found more frequently than to the E6 protein (31.4% vs. 16.8%) when the sera were assayed by peptide-based ELISA. In contrast, when RIPA was employed, reactivity to either protein was obtained at similar frequency (38.7% vs 46.7%). When the protein was denatured prior to immuno-precipitation the reactivity was lost in all sera tested for E6-specific antibodies but only in a few samples in the E7-RIPA. Therefore it was concluded that the increased sensitivity of the E6-RIPA as compared to the E6 peptide-ELISA is due to the detection of antibodies to conformational epitopes which are presented by the in vitro product but not by the synthetic peptides. Eighty-two sera from healthy donors were tested by HPV 16E6- and E7-RIPA and also by ELISA using the HPV 16E7 protein which was produced in the fission yeastSchizosaccharomyces pombe. One sample reacted each in the E6- and E7-RIPA indicating a high specificity of these assays. The E7 protein-ELISA proved to be less sensitive for the detection of antibodies in cervical cancer patients' sera (22.6% positive) as compared to peptide-based ELISA or RIPA.
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  • 2
    ISSN: 1433-0393
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Zum Thema Die molekularbiologische Diagnostik von humanen Papillomvirus (HPV)-Infektionen und HPV-assoziierten Neoplasien des unteren Genitaltrakts erfolgt gegenwärtig ausschließlich durch DNA-Nachweisverfahren. Hierbei kommen sowohl amplifizierende als auch nichtamplifizierende Methoden zum Einsatz. Bei den nichtamplifizierenden Verfahren hat sich der „hybrid capture assay“ durchgesetzt, der kommerziell verfügbar ist und mit dem ein Gemisch von 13 High-risk (HR)- oder 5 Low-risk (LR)-HPV-Typen nachgewiesen werden kann. Der Test ist inzwischen semiautomatisiert und hat sich in mehreren klinischen Studien bewährt. Bei den amplifizierenden Verfahren werden ein System mit degenerierten Konsensusprimern und ein weiteres mit nichtdegenerierten Konsensusprimern angewandt, die beide eine spezifische Sequenz aus dem L1 offenen Leseraster von verschiedenen HPV-Typen amplifizieren und den Nachweis von ca. 10 HPV-DNA-Kopien ermöglichen. Auch mit den amplifizierenden Verfahren kann ein breites Spektrum von HR- und LR-HPV-Typen in einem Test mit hoher Spezifität identifiziert werden. In der klinischen Anwendung kann die HPV-Diagnostik im Rahmen der Vorsorge zur Augmentierung der Zytologie, als Triage für die Abklärung fraglicher zytologischer Veränderungen und als Prognosefaktor für die Einstufung des biologischen Potentials von leichtgradigen Präkanzerosen eingesetzt werden. Mehrere Studien konnten zeigen, daß für die Vorsorge und für die Abklärung unklarer zytologischer Befunde die HPV-Diagnostik eine deutliche Verbesserung der bisher üblichen Algorithmen erlaubt. Bei der Therapie von benignen HPV-assoziierten genitalen Erkrankungen ist die Chemodestruktion mittels Podophyllotoxin oder Trichloressigsäure sowie die physikalische Destruktion mittels CO2-Laser, Kryotherapie oder elektrochirurgischer Abtragung das Mittel der Wahl. Die Behandlung mit Interferon zeigte keinen reproduzierbaren positiven Effekt, potentielle Erfolge mit neuen Immunmodulatoren müssen erst verifiziert werden. Krebsvorstufen sollten nach kolposkopischer und histologischer Evaluierung mittels Knipsbiopsie durch chirurgische Exzision mittels Hochfrequenzschlinge oder CO2-Laser behandelt werden. Beide Verfahren zeigen gegenüber der klassischen Messerkonisation eine geringere peri- und postoperative Morbidität. Interferon sollte bei der adjuvanten Behandlung von Präkanzerosen nur beim Rezidiv oder ausgedehnter Erkrankung eingesetzt werden. Die Wertigkeit neuer Immunmodulatoren wie Leukonorm muß erst in prospektiven randomisierten Studien gezeigt werden. Die ideale Prophylaxe und Therapie von HPV stellt die Impfung dar. Ergebnisse im Tiermodell zeigen, daß eine Prophylaxe möglich ist. Erste Ergebnisse der therapeutischen Vakzinierung beim Menschen sind noch wenig aussagekräftig. Für die Zukunft scheinen chimäre virusähnliche Partikel als idealer Impfstoff, da sie sowohl prophylaktisch als auch therapeutisch wirken können.
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  • 3
    ISSN: 1432-8798
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The low expression of major histocompatibility complex (MHC) class I antigens on human papillomavirus (HPV)-infected cervical carcinoma cells may be responsible for an insufficient cytotoxic T cell response against these cells. To investigate in vitro whether the HPV type 16 early gene product E7 influences cell surface expression of MHC class I and II molecules the HPV negative keratinocyte cell line HaCaT was either stably transfected with the E7 gene or infected with E7-recombinant vaccinia viruses. No difference in MHC class I transcription was detected between E7-transfected and untransfected HaCaT cells. MHC class I cell surface expression as determined by FACS analysis was stronger in some of the transfectants and less intensive in others when compared to untransfected HaCaT cells. In wildtype as well as in E7-recombinant vaccinia virus infected HaCaT cells downregulation of MHC class I molecules on protein and transcriptional level was observed. The alterations in MHC class I expression were independent of the presence and amount of E7-specific transcripts. None of the transfectants or infected HaCaT cells had MHC class II molecules on their cell surface. Hence, our data did not show a correlation between HPV 16 E7 and MHC expression in vitro.
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  • 4
    ISSN: 1365-2133
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The long-term success of organ transplantation depends on the prevention of allograft rejection and improvement in quality of life for the patients. This has been achieved through better immunosuppressive regimens with lower dosages and a new generation of immunosuppressive drugs. However, these immunosuppressive agents not only impair the patient's reactivity to the graft, but also to infectious organisms, thereby making them more susceptible to opportunistic pathogens. Because of this, organ transplant recipients are predisposed to epithelial malignancies and infections. The majority of transplant recipients will develop warts induced by human papillomavirus (HPV). Some of these viral warts may present with atypical histological features and may progress into squamous cell carcinomas. The risk for cutaneous cancers after transplantation is much higher than in the immunocompetent population. Current therapies for HPV-associated skin tumours mainly depend on the destruction of affected skin areas. These treatment modalities are of limited efficacy and are usually painful for the patients. A promising novel therapeutic agent is imiquimod, an immune response modifier. Clinical efficacy of imiquimod has been observed for different skin lesions, including viral warts in both immunocompetent and immunosuppressed patients.
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  • 5
    ISSN: 1365-2133
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Toll-like receptor (TLR)-7 agonists represent a new group of immune response modifiers, which include imiquimod and resiquimod (R-848). Topically applied imiquimod is used for the treatment of both external and perianal genital warts, and benign and malignant epithelial lesions. Based on the induction of interferons and other cytokines in vitro and in vivo, regression of epithelial lesions probably depends on induction of both innate and cellular immune responses. As clinical remission is not always associated with inflammation, other mechanisms may also be involved. Using two different assays for detection of apoptosis (TUNEL test and gel analysis of DNA fragmentation), we observed induction of apoptosis by imiquimod in human epithelial cell lines (HeLa S3) and keratinocytes (HaCaT, A431 cells), as well as in mouse fibroblasts (McCoy cells). These findings suggest that the mode of action of imiquimod to eliminate virus-infected, dysplastic or neoplastic epithelial cells may also include the induction of apoptotic processes.
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  • 6
    ISSN: 1365-2133
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Premaligant and malignant epithelial lesions are acknowledged as being the most frequent neoplasia in long-term immunosuppressed patients such as organ-transplant recipients. Paralleling the constant improvement in modern transplant techniques, their incidence increases together with the growing survival time post-transplantation, reaching 40% to 60% after 20 years. Against the background of lifelong immunosuppression, the impact of accepted cancer inducers and promoters such as ultraviolet radiation, oncogenic viruses and individual susceptibility has to be closely scrutinized. Precancerous lesions such as actinic keratoses in transplant patients progress more rapidly into squamous cell carcinomas, showing an increased tendency to metastasize. As it remains impossible to identify and consequently treat those lesions that may progress into invasive carcinoma, the best prophylaxis for nonmelanoma skin cancer in organ-transplant recipients may be the treatment of all existing precancerous lesions. As reduction of the immunosuppressive therapy is rarely practicable, other terms of prophylaxis and treatment, such as immune response modifiers, have to be considered.
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